Electrical testing instrument



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June 24, 1930. A, H. BENSON 1,765,479

ELECTRICAL TESTING INSTRMENT Filed April "7, 1927 2 Sheets-Sheet 2 y L,9 n@

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Patented June 24, 1930 PATENT `OFFICE:

.ADOLPH E. BENSON, F MIGHIGAMME, :MICHIGAN ELECTRICAL TESTING INSTRUMENTApplication :filed .April 7,

My invention aims to provide an improved testing instrument forelectrical apparatus such as ignition coils, magneto armature windingsand the like.

One of the objects is to provide a simple and compact tester that may bemade and sold very cheaply and that may be used to determine faults ordefective wiring in the ignition systems of automobile engines, magnetowindings, spark plugs and the like.

Other objects and advantages of my invention will appear in thespecification, when considered in connection with the accompanyingdrawings wherein I have shown a preferred embodiment thereof and, inwhich,

Fig. 1 is a top plan view of a tester embodying my invention;

Fig. 2 is a view taken Jfrom one side of Fig. 1;

Fig. 3 is a cross sectional view taken on the line 3--3 of Fig. 1;

Fig. 4 is a fragmentary cross sectional view taken on the line 4 4 ofFig.2; and Fig. 5 is a wiring diagram of the tester 2 shown in Fig. 1,showing it lapplied to a high tension induction coil. f

Referring speciiically to the drawings and to the embodiment of theinvention which I have selected for illustrative purposes, my

improved tester, there shown, is carried in a suitable casing 10 such asa wooden box to protect the delicate parts.

Between the side walls of the casing, I have shown an electro-magnet 11having a core 12 projecting through the walls. The coil of theelectro-magnet is adapted to be connected in circuit with a sourceof E.M. F. 13.

shown as a battery (Fig. 5). This circuit preferably includes aninterrupter 14 secured to the casing adjacent to one end of the core 12and a condenser l5 both in the line from one terminal ofthe battery 13and a switch 16 of the push button type is arranged in the line from theother terminal 5 cludes a pivotally mounted leaf spring 18 o thebattery. This arrangement is some 1927. Serial No. 181,769.

(Fig. 4) having one end pressing against the under side of the armaturespring and the other end, beyond the pivot bearing, arranged to beadjusted by a thumb screw 19 whereby to regulate the speed of thevibrator and thus the induced voltage passing through the variouscircuits of the apparatus to be tested. Moreover, in a recess in the endof the core I provide a piece of fibre or other non-magnetic material19a to prevent the armature from sticking due to residual magnetism inthe core after the current is cut ott'.

At the opposite end of the core 12 of the electro-magnet, is anotherinterrupter 20 which is identical with the interrupter 14, likewiseincluding a shunting condenser 21 which can be cut out by a switch 22,in its circuit but this circuit is adapted to be connected to theapparatus to be tested provided it does not include a. condenser. Inthis instance lead wires 23 andr24 are connected to one terminal of thep winding 25 and to one terminal of the secondary winding 26,respectively, o a high tension induction or ignition coil.

The lead wire 24 as shown in the wiring diagram, is connected by a leadwire 27 in circuit with the positive terminal ofthe battery, while theopposite terminal of the primary coil 25 is connected by a lead wire 28in circuit with the negative terminal of the battery. Across the lowerterminal of the secondary winding 26 and the lead wire 27, I interposean adjustable spark gap 29.

The circuits just described are complete for conducting a test of anordinary high tension, ignition coil which is not provided with aninterrupter. For convenience from the standpoint of packing as well aspractical application, I have shown jacks 30 in the casing 10 forstandard jack plugs 31 on the various pairs of lead wires and I providesuitably colored or numbered spring clips 32 (Fig. 1) on the ends oi thewires to enable an operator quickly to apply them in accordance withsimple instructions.

When the Vcoil is connected as shown in Fig. 5 and the switch 16 isclosed, current from the battery passes through the interrupter 14 andthe Winding of the magnet 11.

The interrupter functions in the manner of the well known buzzer andperiodically i opens and closes the battery circuit through inductioncoil is in good order.

the magnet winding, thus magnetizing and demagnetizing the core 12rapidly. When the core is magnetized, the contacts of the Vibrator 20are opened and closed. The connections are such that the battery isconnected in series with the primary of the induction coil through theinterrupter 2O and the operation of thisinterrupter causes pulsatingcurrents to low in the primary and induce high frequency currents in thesecondary in the well known manner, if the Such current will be manifestby sparking at the gap 29, and if such spark is fat and of the propercolor, will indicate that the coil being tested is good. A weak spark orthe absence of any spark will indicate a bad or defective kcoil.

By using two interrupters on the one coil, two advantages are obtained,viz: no mechanical interrupter will be employed to cause the coil tooperate, and the coil used to drive the interrupter does not have to beplaced in series with the primary of the coil its ends; and a thumbscrew mounted in a. fixed support and engageable with the outer side ofthe other end of the spring.

In testimony7 that I claim the foregoing as my own, I have hereto aixedmy s1gnature.

ADOLPH H. BENSON.

being t-ested to thus change the resistance of the primary circuit.

The condenser 2l is used only when the coil being tested is not providedwith one and may be used to ascertain a failure of the co1 From theforegoing description, it will be observed, among other things, that myimproved tester eliminates the necessity to employ complicated andexpensive mechanical interrupters; that the simple electro-magneticallyoperated circuit makers and breakers are very compact; that theinstrument is relatively inexpensive and easy to apply to ignition coilsin situ; and, that the operator needs only to give his attention to thecharacter of the spark across the spark gap after he completes thecircuits.

Obviously the present invention is not restricted to the particularembodiment 'thereof herein shown and described. Moreover, itis notindispensable that all the features of the invention be used conjointlysince they may be employed advantageously in various combinations andsub-combinations.

What I claim is:

v1. In an interrupter for electromagnets l' of the class described,aspring armature; a

pivoted leaf spring having one end engaging the underside of thearmature; and an adjustable abutment for the other end.

2. I n an interrupter of the class described, a spring armature; meansfor varying the tension of the armature; said means comprising a leafsprin pivoted intermediate lts ends; one end of t e spring engaging theunderside of the armature intermediate of

